1. Field of the Invention
This invention relates to an improvement in a bearing beam structure installed to the bottom part of a cylinder block in order to rotatably support a crankshaft of an automotive internal combustion engine.
2. Description of the Prior Art
In usual automotive internal combustion engines, a crankshaft is rotatably supported through bearing metals by a plurality of bearing sections formed at the bottom part of a cylinder block and a plurality of bearing caps which are secured respectively to the cylinder block bearing sections. The bearing caps are installed in positions separate and independent from each other, and accordingly tend to vibrate in the fore and aft directions (in the direction of the crankshaft axis) to come down under the influence of vibration input from the crankshaft due to combustion impact force. This excites the vibration of the skirt section of a cylinder block, thereby emitting considerable noise. In view of this, a bearing beam structure has been proposed in which a plurality of bearing caps are integrally connected with each other by means of a rigid elongated beam located at the bottom part of each bearing cap section. Such a bearing beam structure is effective for preventing each bearing cap from vibrating in the fore and aft directions, but not effective against, for example, the torsional deformation of the cylinder block around the crankshaft axis, thereby allowing noise generation due to such vibration of the cylinder block.